Exemplary embodiments relate to a passive optical network, and more particularly, relate to an optical repeater of a passive optical network of a time division multiple access (CDMA) manner and an optical signal amplifying method thereof.
Various network structures have been proposed to establish a subscriber line. For example, xDSL (x-Digital Subscriber Line), HFC (Hybrid Fiber Coax), FTTB (Fiber To The Building), FTTC (Fiber To The Curb), FTTH (Fiber To The Home), and the like have been proposed. The FTTB, FTTC, and FTTH may be divided into an active FFTx (x=B, C, or H) realized by an active optical network (AON) and a passive FFTx realized by a passive optical network (PON).
The passive optical network may indicate a subscriber network constituting an optical line using passive components such as an optical multiplexer, a demultiplexer, a coupler, and the like. The passive optical network may have a point-to-multipoint structure in which a plurality of optical network terminals (or, units), that is, optical network terminals (ONTs) or optical network units (ONUs) share one optical line terminal (OLT) via passive elements.
The passive optical network may be divided into a Time Division Multiplexing Access-Passive Optical Network (TDMA-PON) and a Wavelength Division Multiplexing Access-Passive Optical Network (WDMA-PON). In the TDMA-PON, data may be transmitted using a time slot assigned to each subscriber. In the WDMA-PON, data may be transmitted using a wavelength assigned to each subscriber.
A typical TDMA-PON may include a bi-directional optical amplifying device for amplifying upward and downward optical signals, respectively. However, in the event that a burst mode transfer manner is applied to the typical TDMA-PON, it is difficult to provide a stable service due to influence of a noise caused when an optical signal is amplified. For this reason, it is difficult to increase a subscriber number and a distance of distinct transmission.